Posted
by
samzenpus
on Monday January 14, 2013 @11:42AM
from the threads-that-bind dept.

Zothecula writes "At about 100 times the strength of steel and a sixth the weight, with impressive electrical conductive properties, carbon nanotubes (CNTs) have promised much since their discovery in 1991. The problem has been translating their impressive nanoscale properties into real-world applications on the macro scale. Researchers have now unveiled a new CNT fiber that conducts heat and electricity like a metal wire, is very strong like carbon fiber, and is flexible like a textile thread."

Presumably AC is referencing the film [wikipedia.org] but the vanity of people is such that if some fibre allowed permanently enduring clothes they would still want new ones; there will always be a desirable new ironic slogan for a t-shirt.

Now indestructible clothes with a programmable visual component... one would probably do me.

Indeed. I remember hearing that the Salvation Army has to discard something like 90% of the clothing donations they receive simply because the supply so outstrips the demand. Hopefully all that cloth gets turned into insulation or cloth paper or something instead of just ending up in a landfill somewhere. What a waste.

There are various recycling methods, depending on how well you can separate the goods(If a given synthetic type is isolated well enough, you can melt it back to pellets, some fibers are long enough that you can shred and re-process them into rag, or industrial felt, or similar low quality fiber aggregate stuff. If you can screen enough of the synthetics out, it is probably compostable, and I'm sure that baled fabric is hardly the worst fuel that we've ever burned for energy); but it isn't exactly as clean a

I was referring to the second-hand stores, which sell donations as part of the fundraising mechanism for their overseas endeavors. Honestly though I think if you're worried about destroying local markets (which is admittedly a very real problem with most traditional international aid programs) it'd probably still be better to give people clothes than food, simply because it's so much less important of an industry. I quite agree that the smart/sustainable way would be to buy food/clothing/etc locally so th

here are probably niche exceptions; but in most of clothing it's been quite some time since disrepair, rather than disuse, has been the driving factor behind consumption. Even relatively easy and low-tech techniques like 'patching' and 'darning' and assorted flavors of mending have fallen out of fashion

Well there's two different things here, that you wouldn't mend it if was damaged isn't the same as saying you wouldn't want it to last longer, it's certainly not the same as disuse. Honestly I've had clothes that I've loved and used but when they're so worn out they'd need patching and darning I've just said okay it's time to let go and buy a new one, if they hadn't worn out I'd keep using them. Particularly darning I think has almost fallen out of the language, I practically never have to look up English w

I'm suddenly reminded of Mr. Gradgrind speaking to schoolchildren in Dickens' Hard Times. "You don't find that foreign birds and butterflies come and perch upon your crockery; you cannot be permitted to to paint foreign birds and butterflies upon your crockery. You never meet with quadrupeds going up and down walls; you must not have quadrupeds represented upon walls."

TFA says it's as strong as carbon fiber, which suggests that they couldn't translate the strenght of nanotubes into macroscale perfectly.

The common claim that CNTs are "100 times the strength of steel" is basically baloney. Sure, they are that strong at the molecular level. But at the molecular level, even iron-iron bonds are far stronger than steel. If we ever figure out how to control the structure of materials so that the strength of individual chemical bonds is preserved in bulk materials, then we would not only have stronger carbon fibers, but we would also have stronger steel.

... If we ever figure out how to control the structure of materials so that the strength of individual chemical bonds is preserved in bulk materials, then we would not only have stronger carbon fibers, but we would also have stronger steel.

It is a special case, but we do have well know examples of how to do this. They are crystals, which are atomically ordered on the macroscale. The manifestation of the strength inherent in the carbon-carbon bond on the macroscale is what bestows upon diamonds their remarkable properties. Single crystal macroscopic parts are manufactured in metallurgy also (turbine blades).

... If we ever figure out how to control the structure of materials so that the strength of individual chemical bonds is preserved in bulk materials, then we would not only have stronger carbon fibers, but we would also have stronger steel.

It is a special case, but we do have well know examples of how to do this. They are crystals, which are atomically ordered on the macroscale. The manifestation of the strength inherent in the carbon-carbon bond on the macroscale is what bestows upon diamonds their remarkable properties. Single crystal macroscopic parts are manufactured in metallurgy also (turbine blades).

We also have bulk commercial applications of it - nickel super-alloys are grown into very large single crystals for use in airplane propellers/turbine fans. There are no grain boundaries - it's just one big crystal.

That said, there's where the people making artificial diamonds are probably really hoping to go: single crystal diamonds grown to custom order shapes.

When we can consistently produce defect-free carbon nanotubes in much longer lengths than is currently possible. Space elevators require near the upper end of CN theoretical tensile strength.
Bolos, Skyhooks and Rotovators on the other hand...

Kevlar weave shouldn't be that difficult to source; I have a pair of jeans with large areas of Kevlar cloth reinforcement in them. Bought it at the motorcycle shop. Excellent way to avoid a bumectomy in the event of a get-off.

You might want to spring for ballistic grade in that case(and definitely not the kind with aesthetically focused neon-dyed kevlar/carbon fiber weave, unless you are planning on blending in at an aquatic rave or something), and possibly choose a less stiff resin for your kevlar/resin composite, to reduce crack propagation and loss of hull integrity around impact sites. Some sort of layering, possibly including non-resin-impregnated multi-ply layers to contain spall and bullet fragments might also be a good p

Spectra would be better (check your own link), and it costs about the same. But the bulk cost of the cable is not a significant cost in this project, any more than the fuel cost is in space launches (a fact that often surprises people to learn). Raw material costs will be effectively zero compared to the flight systems that must be built and operated. Use carbon fiber - it is the best material we have that we know how to actually make in quantity (and it is actually not much more expensive than Kevlar or Sp

You can't grow new carbon; like any other element, it can't be changed without some nuclear fission or fusion process, or radioactive decay. We "recycle" carbon because it's present in the soil and the atmosphere, and living processes (like cotton crops) re-order these hydrocarbons into new forms (leaves, stems, roots, cotton balls, etc.), with the aid of solar energy.

While carbon molecules tend to be highly biodegradable, Carbon nanotubes aren't, any more than diamond is, it all comes down to the chemical structure. In fact buckyballs, a spherical carbon molecule very similar to nanotubes, has been shown to be a potent environmental toxin in quantity - it's small enough to be readily absorbed by cells, but it doesn't get broken down and eventually clogs up the "machinery" to the point that the cell dies, at which point it and it's toxic payload get consumed by somethin

Interesting, though I'd suggest for at least the next extended time period the composition of the mantle and core (the vast majority of the Earth) is largely irrelevant as a resource, it's only the stuff in the crust and atmosphere that is accessible. Still looks like the crust is similar, once you factor for atomic masshttp://en.wikipedia.org/wiki/File:Elemental_abundances.svg [wikipedia.org]

So I suppose it's really just a matter of carbon being really *accessible*, and recycling carbon is likely to become an issue fairl

Actually, in the Earth's crust, aluminum is more common than carbon by a factor of about 200. Only oxygen and silicon are more common. Source. [wikipedia.org]

Talk to a chemEng about the nightmare of aluminium refining. Its not just that the hall process takes a lot of electricity mostly from burning coal, but it only works with alumina. You gotta run raw bauxite thru the Bayer process which is a whole nother PITA to pre-refine it before it hits the electrochemical cells as alumina. Most bauxite comes from Australia and Brazil, and there's only a "couple centuries worth" and then thats it for bauxite, so aside from recycling it'll be back to the old days before the Hall process where Aluminum was basically a precious metal. Aluminum really is a huge unholy pain in the ass to refine into usable metal.

Its kinda like nitrogen. Plants REALLY need nitrogen. But we all live in a great seemingly infinite pool of nitrogen gas, you say so whats the problem. Yeah but biochemically its a PITA to use N2 straight outta the air, so it (mostly) doesn't happen. Leading to all kinds of chemEng foolishness with ammonia and nitrogen fixing bacteria on legumes etc etc.

Having some atoms laying around doesn't mean they're convenient to use, or practical to use, or possible to use.

You have to take standard resource reserve estimates with a grain of salt. Unless they specifically analyze unconventional resources, and all resources at multiple price points above the present market price, you are getting an extremely conservative lower bound estimate on the real resources.

It would be remarkable if the third most abundant element in the Earth's crust (8.2%) would be so "limited in distribution". Bauxite is around 40% aluminum, a modest 5-fold enrichment over the crustal average, there are vast quantities of material (e.g. aluminum clays like kaolin) that are nearly as high, and a commercial production process is already being brought to market: http://www.ammg.com.au/download/IndMin%20-%20Meckering%20making%20alumina%20from%20kaolin%20-%20Sept%2012.pdf [ammg.com.au] . In two hundred years exploiting other aluminum resources won't be a problem.

These are not resource reserve estimates. They are estimates of the abundance of various ELEMENTS, a large part of the total for most of them being tied up in various chemical compounds. They are of scientific interest and make no claim to quantify the ease of isolation, extraction and purification.

The process of making this fiber is to dissolve CNTs in a super-acid and then wet-spinning them into threads. Apparently the key to this process is the same one use to make Twaron [wikipedia.org].

I'm not sure how this process has been adapted to make CNT fibres, but at least in the case of Twaron and Kevlar, dissolving the polymers in normal acids for powderization is a problem so they use a special patented process to do this which consists of NMP [wikipedia.org] and some other stuff. Then they have to wet-spin it into threads from a solution that's pretty much 100% acid (according to the wikipedia, they dissolve the polymer powder by mixing it with frozen 100% sulfuric acid in powder form and gently heating it).

On the surface, it sounds to me that this is a similar level of PITA as refining aluminum...

There's also more Platinum than Gold in Earth's Crust. Platinum is considerably more valuable than Gold, and more useful as well. One would think that we would be mining/smelting far more Platinum, but no, Gold production is 14x that of Platinum.

There's a real difference between the abundance of a material in Earth's crust, and the ability to obtain useful quantities of it. Until we develop the technology to "crack" planets and refine the contents wholesale, relative amounts of an element in the crust is me

It seems to me that if a civilization develops "planet-cracking" technology, and the ability to go to other planets to use such technology for harvesting materials, that same civilization should have the technical ability to simply synthesize whatever materials they need through nuclear fission/fusion processes. The energy to do this is extremely abundant; all they have to do is collect it from a nearby star (they can probably just harvest the hydrogen and helium from that star too, to use to create the el

Is it though? The earth's "crust" is actually a really thick layer, and we haven't even managed to drill through it yet. Here on top of the crust, the concentration of materials is rather different than it is several miles down. The soil that you walk on every day likely has a lot of carbon in it, a lot more than it does aluminum (unless you're walking on the beach, in which case it's mostly silicon you're walking on). Also important to us is what's in the atmosphere; CO2 is a significant portion of the

The article mentions that it still has incredibly high textile strength, and shows a small fiber holding up a light (not much, but still).

I think that cost would scale down well since it's very similar to other material handling.

Right now, a large part of the cost and problems with data cables are the really thin wires -- we'd like them to be thinner, but can't make them any thinner without making the cable too brittle. I purposely buy extra-thick data cables merely to reduce problems in the field due to f

20 angstroms. But that number means nothing to me or anyone else who doesn't regularly work with things that small. It's good journalism to write things your audience can actually relate to and not throw meaningless numbers at them, at least when it's journalism for a general audience.

It's better journalism to give both. "The strands are about 2 nanometers wide or about the width of a strand of DNA." Either just means really small to most people but for those who aren't most people you've provided the important piece of information.

The published ultimate tensile strengths of the CNT fibers in this work is well below that of aerospace-grade carbon fiber. They have a big gap to bridge before the CNTs can be of any use for building airplanes, let alone space elevators. Not saying that it can't be accomplished, but that this not yet a major breakthrough.

The published ultimate tensile strengths of the CNT fibers in this work is well below that of aerospace-grade carbon fiber. They have a big gap to bridge before the CNTs can be of any use for building airplanes, let alone space elevators. Not saying that it can't be accomplished, but that this not yet a major breakthrough.

I'm more interested in if this is cheap or not in mass quantities and practical to be used for wires..

You assume that the price will be lower than copper. Since they are likely to price this as a premium product (lower-weight, more flexible), initially, the price per meter may well be higher than the copper wire it replaces...

That's crazy talk! If the material were actually expensive it would cut into the outrageous profit margins. A little gold-plating on the connectors is only permissible because the actual quantities used are miniscule, and the marketing value is substantial.

Aha, but toughness / 5.4620008x10^17 = tensile strength. I know this because 5.4620008x10^17 is the total force of the bomb dropped at Hiroshima, divided by the area of a football field. Toughness thus joins the league of questionable made-for-TV units of measurement.

I would have to think for awhile about the velocity of propagation. I think Vp would be higher for a hollow (vacuum) carbon nanotube optical fiber which might be an advantage.

I know its barely theoretically possible to make a hollow titanium sphere that is strong enough to hold a vacuum, barely, so it'll float, but not engineering practical to make it. I wonder if you could make a CNT tube that would float in the air. That would certainly reduce optical fiber costs, if you only needed a tower/pole at each end of the run, plus or minus wind forces I guess. If nothing else I think CNT optical fiber would be lighter than glass fiber, for aerospace or whatever. Pity its flammable.

Making a rigid sphere to resist 1 atm differential is easy, the problem is making such a sphere that, when containing a vacuum, is light enough to weigh less then the total weight of air that the sphere displaces. If you can make such a rigid yet light container, you have the potential to create balloons with greater lift capacity than hydrogen filled gas-bags.

What vlm was saying is that the low weight and high strength of titanium makes it feasible (on paper) to create a thin foil sphere of titanium that

The statement was poorly worded. What is not possible is making an evacuated spherical shell of any available engineering material, with a mass no greater than the mass of the air displaced, strong enough not to collapse under atmospheric pressure.

I'll give you a hint. For any available engineering material, the shell would have to be so thin in order to be buoyant, that it would it would instantly crumple due to lack of structural stability.

Of course you could just fill the interior with something slightly more dense than a vacuum and reduce the constraint as required. For instance balloons filled with helium float just fine in the air.

In both cases (vaccum and helium filled), you have to worry about outside air diffusing inside over time. I imagine this is much more difficult of an engineering problem that needs to be solved before this would even be remotely practical. My guess is that this forces the walls to be thicker than the minimum

I know its barely theoretically possible to make a hollow titanium sphere that is strong enough to hold a vacuum, barely, so it'll float

Assuming you're talking about a spherical shell of titanium, evacuated inside, the whole with a mass no greater than the mass of air displaced, and which can withstand an external absolute pressure of one atmosphere, no it is not possible. Decidedly not.

The extent of nano-tube regulation in California was passing a bill (AB289) that authorizes the Department of Toxic Substances Control to request information on environmental and health impacts from nanotube manufacturers and importers. It was authorized to collect information from the industry to use in evaluating hazards and risks (a process completed in 2009).

That's it.

No ban. Not even any regulation at all, whatsoever.

And it seems perfectly reasonable for the DTSC to collect such information. It is not as if completely novel materials, to which humans and other living things have never before been exposed, have never shown any harmful effects.

The California hating automatic reflex - much easier than taking the trouble to actually learn things.